MadeEasy Test Series 2019: CO & Architecture - Pipelining [closed]

Question

5 stage pipeline → 3,6,5,8,4 latencies(in ns).What is average CPI of non pipelined CPU when speed up achieved by to pipeline is 4 ? (ans = 1.23)

Comments

Not able to understand the proper approach and formula to be used..

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just formula need to use

$Speedup=\frac{time for NonPipeline\times CPI_{np}}{time for Pipeline\times CPI_{pipe}}$

$4=\frac{26\times CPI}{8\times 1}$

Now find $CPI_{non-pipe}$

Pipeline CPI=1(known)

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Thanks a Ton.. :)

Answer 1

We know ,Speed up=Time for Non-pipeline/Time for pipeline=Tnp * CPInp/Tp* CPIp

We know,CPI for pipeline =1 Tnp=3+6+5+8+4=26 Tp=max(3,6,5,8,4)=8,Speedup=4(given)

Putting the values ,we get CPI np=1.2